Leaching of a silver bearing sulphide by-product with cyanide, thiourea and chloride solutions

The aim of this research was to increase the value of sulphide tailings assaying 1000–1500 g/ton Ag per tonne and high arsenic (about 13%) content. lphides were characterized and it was verified that silver occurs both as mathildite, AgBiS2, and in solid solution in galena. alternative routes were assessed: cyanidation, thiourea leaching and chloride leaching. anidation route showed that there was a high consumption of cyanide and led to the formation of an insoluble compound of silver thiocyanate. aching with thiourea was achieved without the introduction of Fe3+ but it is not an economically viable route. de leaching of the product in its original particle grain size showed very good extraction even without addition of Fe3+. Operating under [Cl−]≥3 M at 80–90°C for at least 3 h it was possible to dissolve 60–80% of the total silver, and higher recoveries of lead and bismuth were also achieved.